While some still debate the relative merits of direct vs. video laryngoscopy, the newest set of laryngoscopes make it easy, offering the best of both worlds.
While some still debate the relative merits of direct vs. video laryngoscopy, the newest set of laryngoscopes make it easy, offering the best of both worlds.
At the recent Society for Airway Management conference there was a debate on Direct Laryngoscopy (DL) vs. Video Laryngoscopy (VL). While I love imaging and the mechanical and teaching advantages of look-around-the-curve video laryngoscopes, there is beauty in the simplicity, speed, and emergency applicability of direct laryngoscopy. DL is faster and does better with fluids, bleeding, and vomitus while tube delivery is much more straightforward with hyperangulated video devices. When VL is used in large series it does not perform better overall than DL, although there are cases when DL is very hard and VL easy. Alternatively, I have had some hard or impossible VL cases where DL was a slam dunk.
It occurred to me after the conference that the debate was in some ways pointless, given the new array of DL/VL devices which make both options available to you. With hyperangulated devices like the Glidescope, McGrath Series 5, or Storz Dorges Blade video laryngoscope, the angulation of the blade prevents any direct view. If the video fails, from fluids or any other reason, there is no direct view. This is not the case with DL/VL combination devices. Intubation can be done via direct line of sight, just as a standard instrument would be used, or under video, or as a combination. In the setting of emergency airways, especially trauma airways, I think this has great value.
Currently available DL/VL devices include the Storz C-Mac, the new McGath Mac (now to be distributed by Covidien), and the Glidescope Direct Trainer.
After many years of testing in real tissue I appreciate that hyper-angulated video laryngoscopes can provide a fuller view of the larynx than DL/VL devices in many cases. However, I have found extremely few cases where DL/VL devices did not provide enough imaging of the larynx–under video–to successfully intubate, even if the DL view was not adequate. I do appreciate that in elective anesthesia there are advantages to using a hyper-angulated narrow flange device, like the Glidescope, that avoids excessive forces on teeth and tongue and jaw. In the elective setting there is also little concern for fluids, secretions, vomitus. While I believe many of the video devices, and particularly the Glidescope (due to its camera position and the angle of the lens over the camera) function remarkably well in most soiled airways, though things can still obscure the view. If anything obscures the view the device must be removed and wiped, or another intubation method tried, because there is no direct view of the larynx. The overall failure rate of either DL or VL (with a Glidescope) is in the 1-2% range (or less). There are as yet no large studies looking at the failure rate of DL/VL devices, but I think the emergency airway may be the best place to deploy these products.
Regardless of which device you favor, or which device you use, remember a few simple rules to make your airways as uneventful as possible:
1. Apply nasal cannula to every emergency airway (under mask during pre-oxygenation) and flow it at high rate (15 lpm) throughout the DL or VL [Nasal Oxygen During Efforts Securing A Tube—NO DESAT]. It’s fun watching the pulse ox rise during apnea (after muscle relaxants). It has become a major stress reducer in my airway cases. For more information look up my prior article in EP Monthly (goo.gl/aX8kJ), or check out a new article I just published with Scott Weingart on Oxygenation in Annals of Emergency Medicine.
2. Have the Yankauer in your right hand, and suction aggressively prior to insertion of any device. As you begin to insert the blade, dab the posterior pharyngeal wall–with either DL or VL.
3. Always, always, always do epiglottoscopy before laryngoscopy–with both DL or VL devices. Find the epiglottis first, before you expose the larynx. This makes the procedure reliable, since the epiglottis is the on-ramp to the larynx, at the base of the tongue where you start, and at the top of the laryngeal inlet and larynx (where you’re going). Never hyper-extend the head on the neck; ear-to-sternal-notch positioning, face plane parallel to ceiling prevents the posterior displacement of the base of the tongue and epiglottis onto the pharyngeal wall, and will make jaw distraction and epiglottis identification easier.
1. The Glidescope Direct Trainer has a relatively flattened American Macintosh blade shape and can be plugged into the same monitors used by the regular Glidescope. The blade is metal and currently does not come with any removable/single-use covers, although I have been told this option will be available soon. The blade must be cold sterilized between patients, not autoclaved.
2. The Storz C-Mac was the original of the DL/VL devices. Its metal blade has a German Macintosh shape. This refers to the relatively low proximal flange height, the full flange from base to tip, and a short light-to-tip distance. The video and light source comes through a removal cartridge that slides in and out of the blade handle. Like the Glidescope Direct Trainer the blade requires cold sterilization and there as of yet no single-use covers, although they too are in the works. The Storz product has a very bright light and a somewhat closer view of the larynx than the Glidescope Direct Trainer. It plugs into a separate monitor like the Glidescope, although the company has just created a self-contained small monitor that is part of the camera/light cartridge for a more portable solution. The power and monitor turn off when this small screen monitor is folded down. Just as different blades can be plugged in with the Glidescope, the Storz monitor also accepts its new hyper-angulated Dorges Blade (which has more of a Glidescope blade shape).
3. The McGrath Macintosh is a new product from Aircraft Medical. It will be sold in the US by Covidien, a large and diverse medical products company whose brands include Nellcor and Mallinkrodt. The McGrath Mac is entirely self-contained with a small integrated LCD screen. It has a very low profile Macintosh blade design and uses single-use clear plastic blades that quickly fit on and off. It has been designed like the Glidescope Ranger to meet military specifications, namely that it can be dropped from 6 feet, frozen, immersed, etc…presumably able to handle the abuse it will get in the chaos of the emergency department. The device uses a small button battery pack that must be obtained from the company. A nice feature of the product, considering that it is battery-run only, is that a small clock provides information on how many minutes of run time are left on the battery pack. Relative to the Glidescope Direct or the Storz C-Mac the light (and image on the small portable screen) was not as bright, although the screen and light have just been upgraded. I have yet to test this newer version in my lab.
Dr. Levitan teaches emergency medicine at Jefferson Medical College and at the Univ. of Maryland and helps run a mo
nthly airway management course involving specially prepared cadavers:
jeffline.jefferson.edu/jeffcme/Airway
